Pablo Martinez Monsivais/The Associated Press archive'we wanted to make sure BP understood we expected this data to be made publicly available and in a timely manner,' Environmental Protection Agency Administrator Lisa Perez Jackson said.

The dispersant directive was issued by Environmental Protection Agency Administrator Lisa Perez Jackson, while both Jackson and Secretary of Homeland Security Janet Napolitano wrote BP Group Chief Executive Tony Hayward in London asking that BP turn over on a daily basis all relevant information and post it on a publicly accessible website.

"This includes, but is not limited to, any and all sampling and/or monitoring plans, records, video, reports collected by BP, its contractors, subcontractors, agents or employees, any such reports that have come into BP's possession through other means, and any reports of internal investigations," Napolitano and Jackson wrote Hayward in a letter copied to Lamar McKay, the chairman and president of BP America.

McKay has faced frequently hostile questioning in the past two weeks from members of Congress at a series of hearings looking into the April explosion at BP's Deepwater Horizon oil rig and the massive and still-growing spill that followed.

"BP has been taking a lot of data at the direction of government and we wanted to make sure BP understood we expected this data to be made publicly available and in a timely manner," Jackson said. "We're hoping by doing that, folks will have a sense of not only how much has been done but also get information to let them draw their own conclusions."

Jackson said there is "so much misinformation going out and it's not fair to people on the Gulf Coast and certainly not fair to fishermen and shrimpers that people are going to spread misinformation or sensationalize things. We just need to get the data out there."

Amid demands for more information, BP began providing a live video feed of oil gushing from the site of the leak late Wednesday, and at a news conference Thursday, U.S. Reps. Henry Waxman, D-Calif., chairman of the House Energy Committee, and Edward Markey, D-Mass., chairman of twin climate and energy panels in the House, said that BP's failure to be more forthcoming with the video earlier demonstrated, in Markey's words, that "we cannot trust BP."

Asked about that, Jackson said the failure to provide the video earlier had "left a sour taste in people's mouths."

According to the new directive on dispersants, BP has 24 hours to identify from an EPA-approved list a less toxic alternative to Corexit, the dispersant it has been using both on the surface and below, and 72 hours to begin using that alternative.

The EPA has begun posting results from the ongoing monitoring of BP's use of underwater dispersants in the Gulf online at www.epa.gov/bpspill.

"Nothing in the tests we have in this round of data indicate the dispersants are doing anything but making the situation a bit better," Jackson said. But, as the crisis has worn on, "we are talking about a level of dispersant that is unprecedented. We really just felt that it was time for them to take a look at this."

In his examination of McKay at Wednesday's hearing of the House Transportation and Infrastructure Committee, New York Democrat Jerrold Nadler suggested that BP chose Corexit because it had a corporate connection with its maker, Nalco.

"Why would you use something that is much more toxic and much less effective, other than you have a corporate relationship with the manufacturer?" Nadler asked.

BP spokesman Scott Dean said Friday that "Corexit was readily available in the quantities required by the spill response plan, which was preapproved by the government for use in spill response. It has been very effective in causing the oil to form into small, isolated droplets that remain suspended until they're either eaten by naturally occurring microbes, evaporate, are picked up or dissolve."

But at Wednesday's hearing before the House Transportation and Infrastructure Committee, Sylvia Earle, the National Geographic's scholar in residence, testified that "the instructions for humans using Corexit, the dispersant approved by the EPA to make the ocean look better, warn that it is an eye and skin irritant, is harmful by inhalation, in contact with skin and if swallowed, and may cause injury to red blood cells, kidney or the liver."

"People are warned not to take Corexit internally," she said, "but the fish, turtles, copepods and jellies have no choice."

In a letter to Jackson, Markey had questioned whether Corexit might also be contributing to reports of large undersea "oil plumes" thousands of feet below the surface.